Non-Ideal Compressible-Fluid Dynamics Simulations in Orc Turbines with a Discontinuous Galerkin Solver

This work aims to show the new capabilities implemented in an in-house discontinuous Galerkin solver for the numerical simulation of Organic Rankine Cycles turbine stages. The RANS equations coupled with a turbulence model are solved to predict the flow features in a multi reference frame, where interfaces between fixed and rotating zones are treated with a mixing plane approach and non-reflecting boundary conditions are used. The thermal pressure-explicit equation of state of Peng-Robinson is used to accurately relate thermodynamic quantities and is supplemented by a polynomial description of the ideal gas contribution to the isobaric specific heat. The solver is assessed with the computation of the flow field through the first stage of an existing axial ORC turbine provided by Turboden S.p.A..